This invention relates to the use of a Raster Scan CRT Display to display sonar and related data. The present invention is concerned with displaying scanned sonar data with a correspondence of depth and direction to a given area on the CRT screen. This correspondence comes from coupling the direction of the transducer with the data shown on the CRT screen.
There are no low cost scanning sonars on the consumer market although they have been used by the military and to a lesser degree commercially for many years. In "Electronics", June 1946 page 126 Finn J. Larsen reported on the Ultrasonic Trainer AN/APS-T3 which was a scanning sonar used to emulate radar. A servo motor was used to rotate the transducer to simulate the rotation of a radar antenna.
A typical scanning sonar is described in U.S. Pat. No. 2,865,014 isued to R. H. Malm in Dec. 16, 1958. This sonar presents eata in a plan position indicator (PPI) or polar coordinate presentation. The phosphor of the CRT is used as the memory element. The transducer can be tilted and rotated and is driven by a geared closed loop servo system.
There is similarity between sonar and radar scaning systems in there presentations. Most of the scanning systems present data in polar coordinates although some use the x-y presentation. The AN/TPN-8 Radar has both the PPI and the x-y mode of presentation as described in the "Technical Manual Radar Set AN/TPN-8" approved Dec. 12, 1962 NAVSHIP 0967-104-1010.
The basic reason that scanning sonars are not on the consumer market is that they are too expensive and are not easily portable. Another reason is that most scanning sonars are too massive for small boats due to the use of massive geared drive systems which use expensive closed loop servo drive systems. However, sonar depth finders, sonar chart recorders and sonar CRT chart recorder type devices enjoy great popularity. There is a need for a sonar scanner which will compete in price with the CRT chart recorder and also be as portable.
It is the primary objective of this invention to provide a simple, reliable, portable and inexpensive scanning sonar display system for the consumer market. This is possible because of the unique methods of implementation which are described in this specification.